Multiple simultaneous link transmissions for a multi-frequency multi-rate multi-transceiver communications device

ABSTRACT

An apparatus includes a network node configured to communicate with other network nodes via a communication network. The network node includes a plurality of transceivers and a controller. The controller includes a link management module and a packet management module. The link management module is configured to produce link profiles associated with communication links available to the network node, wherein a link profile indicates link characteristics that include a busy indication of a transceiver. The packet management module is configured to identify a link profile solution set that includes a set of link profiles corresponding to communication links for multicasting the message packet, map the link profiles of the link profile solution set to at least a portion of the plurality of transceivers, and initiate transmission of the message packet using the communication links corresponding to the link profile solution set.

RELATED APPLICATION

This application is related to patent application Ser. No. titled“Interface and Link Selection for a Multi-Frequency Multi-RateMulti-Transceiver Communications Device” (attorney docket no.3547.009US1), and to patent application Ser. No. titled “Just in TimeLink Transmission for a Multi-Frequency Multi-Rate Multi-TransceiverCommunications Device” (attorney docket no. 3547.011US1), both of whichare filed concurrently herewith.

GOVERNMENT RIGHTS

This invention was made with United States Government support underContract Number FA8750-11-C-0201. The United States Government hascertain rights in this invention.

TECHNICAL FIELD

Embodiments pertain to communication systems. Some embodiments relate toa communication network of multi-transceiver network nodes.

BACKGROUND

There is continued demand to improve the performance of wireless (e.g.,radio frequency or RF) communication networks. For example, militaryapplications can require multicast transmissions of video information.Multicast transmissions are messages that are transmitted simultaneouslyto many target nodes from one source node. In contrast, unicasttransmissions are point-to-point from node-to-node. The requirements ofthese multicast transmissions impose significant demands on networkcapacity and delay in delivery.

One way to improve network capacity is to use network communicationnodes that have multiple transceivers, or a multi-transceiver system. Amulti-transceiver system often involves a dedicated signaling channeland N≧1 data channels. All nodes of the system typically assign the samesignaling channel, which is intended for control packets. If a node hasmore than one data link to its next-hop target, it may use the channelwith the highest signal-to-interference noise ratio (SINR) or the nextidle channel. However, one issue with present multi-transceiver systemsis that they typically focus solely on unicast message traffic and donot accommodate broadcast or multicast traffic. Broadcast traffic refersto transmitting information received by every node on the network.Multicast traffic refers to transmitting information to multiple nodeson the network simultaneously, but to less than all nodes. For systemswith protocols that do accommodate broadcast traffic, the broadcasttraffic is typically sent using the dedicated signaling channel orcontrol channel. This can limit the scalability of the network andreduce efficiency of network node use.

Thus there are general needs for systems and methods that improvecommunication network throughput and reduce communication delay whileimproving network robustness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of portions of an example of a network node ofa wireless communications network in accordance with some embodiments;

FIG. 2 illustrates an example of message packet routing in accordancewith some embodiments;

FIG. 3 shows an example of an implementation of neighbor node and linkprofile structures in accordance with some embodiments;

FIG. 4 illustrates determining a busy status of transceivers astransceiver queues fill up and empty; and

FIG. 5 is a flow diagram of operating a multi-transceiver network inaccordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

As explained previously herein, there are advantages to implementing amulti-transceiver network to improve network throughput. Some networksprovide for frequency-hopping that allows a node to leverage multiplefrequencies and avoid jammed or busy channels. However, frequencyhopping is usually limited to unicast transmissions and is dedicatedbetween a single transceiver at the source and a single transceiver atthe target.

Some networks, such as military application networks, need to be quicklydeployable self-building and adaptable. Communication devices can usedifferent communication interfaces such as Bluetooth™, WiFi, Cellular 3Gand 4G networks, GPS etc. It is desirable for non-homogenoustransceivers to communicate with different neighbor nodes, and implementfrequency-hopping using different neighbor nodes and differentcommunication channels. It is also desirable for network nodes to beable to adapt to a changing network.

Network Architecture

FIG. 1 is a block diagram of portions of an example of a network node100 of a wireless communications network. In some examples, the networknode 100 can be included in a cellular telephone. In some examples, thenetwork node 100 is included in a wide area communications network. Incertain examples, the WAN include portable communication devices. Incertain example, the WAN is implementable for battlefield applications.

The network node 100 communicates with other network nodes via thecommunication network. The physical layer or PHY layer 105 includes aplurality of wireless transceivers (not shown). The network node 10 alsoincludes a controller 110. The controller 110 can include modules andsub-modules to perform the functions described. A module can includehardware, firmware, or software or combinations of hardware, firmware,and software. The controller 110 can include a processor such as amicroprocessor or other type of processor to perform software orfirmware instructions.

The controller 110 includes a medium access control (MAC) module 115 tocontrol access to communication channels via the transceivers. MACmodule 115 interfaces to a dynamic spectrum access (DSA) module 120. TheUSA module detects or finds acceptable frequencies for communication andevacuates channels where non-cooperative signals (NCs) are detected.Examples of NCs include jamming signals or noise. The DSA module 120 canreconstitute a network topology to avoid NCs and can make the networkfree of NCs.

The MAC module 115 includes a link maintenance (LM) module 125. The LMmodule 125 performs neighbor node discovery across frequencies and datarates and creates links on which to reach neighbor nodes. The LM module125 of the network node 100 can include a frequency assignment (FA)sub-module (not shown) to assign frequencies or channels to the multipletransceivers to maintain a connected network.

The MAC module 115 also includes a packet management (PM) module 130.The PM module 130 provides a point of interface to a Routing module 150for message packet routing, queue management and message aggregation.The PM module 130 also determines a set of links that are used to reachthe next-hop targets for frequency hopping. The Access module 135arbitrates access to the channel using a variation of Carrier SenseMultiple Access with optional Collision Avoidance (CSMA/CA). Eachtransceiver of the multiple transceivers is controlled by a separateAccess Worker sub-module or thread 140A-D. The group of worker threadsis coordinated by an Access Controller sub-module or thread 145.

A challenge is to find the best combination of transceivers on which tosend multicast or broadcast packets.

A. Dynamic Spectrum Access

The nodes of the network can be cognitive radios that form aself-constructing network that can operate in the presence of NCs. TheDSA module 120 provides frequency channels (and their bandwidth) forassignment by the MAC module 115 while conforming to the regulatorypolicy of the network. Reasoning by cognitive radio refers tointerpreting regulatory policy and results from channel sensing todetermine whether a frequency can be used for communication.Channelization by cognitive radio refers to creating usable channels outof ranges of frequencies determined by the Reasoning. In order toprovide service under the presence of NC conditions, jammed frequenciesare detected and evacuated in an orderly manner. Sensing by cognitiveradio refers to quieting the nodes within a two-hop node radius andlistening for activity on the communication medium. The results ofSensing are passed to Detection for spectrum evaluation andidentification of NCs. Finally, Evacuation and Reconstitution bycognitive radio is responsible for abandoning a jammed channel andconnection of a network node on undisturbed communication channels. Insome examples, the DSA module 120 performs the Reasoning and theDetection functions of cognitive radio, and the MAC module 115 caninclude a Channelization sub-module, a Sensing sub-module and anEvacuation and Reconstitution sub-module to perform those functions ofcognitive radio. Other divisions of the functions of cognitive radio arepossible.

1) Reasoning: The DSA module 120 chooses frequencies to use forcommunications while conforming to a regulatory policy. The regulatorypolicy can be an ontology describing which frequencies may be authorizedfor a given geographical area or within a regulatory domain. Theregulatory policy may be complex and can change with time. The networknode 100 listens for other authorized users (called “primary users” or“non-cooperative users”), and refrains from transmitting on thefrequencies if the users are present. Reasoning may include parsing oneor more of the regulatory policy. NC detection and physicalcharacteristics of a channel to determine and prioritize frequenciesthat may be assigned by the MAC module 115.

2) Channelization: The Channelization sub-module may break downfrequency ranges into channels (e.g., a center frequency and abandwidth) that can be assigned to physical multiple transceivers. TheChannelization sub-module may ensure that the maximum number ofnon-overlapping non-interfering channels can be created out of theavailable frequencies.

3) Sensing: At the core of cognitive radio is a key component of aregulatory policy that proposes that a spectrum or section of spectrumbe used on a secondary basis when the primary user is not using it.Thus, the Sensing function of cognitive radio checks for active primaryusers and other non-cooperatives. The DSA module 120 may send requeststo the MAC module 115 to schedule sensing time. For each sensinginterval, the DSA module 120 may provide a list of channels to sense andthe sensors to be used. The MAC module 115 may hush the frequencies thatare in use within a two-hop radius of the network node 100. To hush thefrequencies, the MAC module 115 may broadcast control messages calledDefer To Sense (DTS), which may indicate the time to the next sensingperiod and the duration of the sensing. Network nodes may try tocoordinate their sensing periods to increase channel utilization.Finally, the MAC module 115 engages the sensors whose results are thenpassed to the Detection by the DSA module 120 for spectrum evaluation.

4) Detection: The DSA module 120 uses the sensing results to determinewhether a channel should be evacuated. The DSA module 120 may examineenergy in either large swaths of spectrum or narrow bands and maycharacterize non-cooperative signals (i.e., non-network nodes,primary/legacy users of the spectrum, jammers), network node chatter andthe channel's noise floor.

5) Evacuation and Reconstitution: As a result of performing Sensing andDetection, the DSA module 120 creates and maintains a dynamic list ofchannels for the MAC module 115 to assign to transceivers. When apreviously allowed channel becomes disallowed due to a non-cooperative,the MAC module 115 is immediately informed so that Evacuation andReconstitution can be performed. The Evacuation and Reconstitutionsub-module performs these tasks when a frequency is removed from use. Akey part of Reconstitution is to provide multiple channels to the MACmodule 115 and to perform robust connectivity so that the loss of anychannel does not partition the network. Only systems with multipletransceiver nodes can provide continuous network connectivity at a timeof Evacuation. Special control packets sometimes referred to asHeartbeats or Beacons can carry the necessary connectivity informationbetween network nodes.

B. Link Maintenance (LM)

The LM module 125 may perform one or more of discovering new directlyreachable nodes (sometimes called “neighbors”), dynamically assigningfrequencies to transceivers, tracking the communication links toneighbors available on those frequencies and advertising thecommunication link status to the Routing module 150 for packet routing.The LM module 125 can include an FA sub-module. The FA sub-module canassign multiple frequencies to each network node, which can greatlyincrease network capacity.

1) Frequency Assignment in Multi-Transceiver Systems: The FA sub-modulemay assign distinct frequency channels to each available transceiver ina manner that achieves the desired network connectivity and networkproperties. This allows the network to adapt the assignments to thedynamics of the network neighborhood and of Non-Cooperative signals(NCs), and facilitates blind neighbor discovery.

When the network node 100 is activated, it may first attempt to discoverother nodes and their frequency assignments. The FA sub-module may startthis process by “soft-assigning” the first available transceiver to arandomly chosen frequency and sending periodic probe messages. Betweensending the probe messages, the network node may listen for messagepackets from neighbors while cycling through its available frequencies(e.g., “scanning”). Network nodes may exchange information about theirfrequencies and assignments through Heartbeat messages. After a networknode discovers its neighbors and learns their assignments, it“hard-assigns” the first transceiver to the eligible channel (as definedby the eligibility functions discussed below herein) with the mostpotential neighbors.

The FA sub-module may perform a channel selection algorithm usingdifferent eligibility functions, and using the different eligibilityfunctions results in different network topologies. The purpose ofchannel eligibility is to decide which channels are eligible forassignment according to a given or specified design constraint. Thedifferent eligibility functions can be designed and implemented suchthat one eligibility function may be replaced with another eligibilityfunction without affecting the rest of the functions of the FAsub-module. Some examples of eligibility functions include a CliqueEligibility Function, a Tile Eligibility function and a BlanketEligibility Function.

The Clique Eligibility Function provides topological frequencyseparation. A channel C is deemed to be an ineligible channel if anothertransceiver has already been assigned the channel, or if such anassignment would result in a two-hop path involving nodes X-Y-Z, whereall three nodes have channel C as one of their transceiver assignments.Identifying Cliques of nodes where the nodes cannot all be assigned aspecific channel eliminates hidden terminations because there are nosituations where a node that is two hops away is sharing the samefrequency. However, forming Clique Eligibility can result in adisadvantage in multi-rate network environments where only one frequencyper transceiver of a Clique can be assigned within an area equal to alowest data rate (LDR) communication range, because the LDRcommunication range often includes the whole network.

The Tile Eligibility Function spreads neighbors among availabletransceivers. The channel C is deemed eligible if the number of one-hopneighbors using C is less than the tile size. The tile size is definedas a network node's number of neighbors divided by its number oftransceivers. As neighbors appear and disappear, a network node's tilesize may change over time. There can be a trade-off between updatingtransceiver assignments to the top eligible or most desirable channeland the cost of un-assigning and re-assigning channels on a transceiver.The algorithm of the Tile Eligibility Function is designed to update atransceiver channel assignment only if the neighborhood changes beyond apredetermined threshold (e.g., a number of channels of neighbor nodesare changed that exceeds a channel change threshold).

The Blanket Eligibility Function is designed to ensure end-to-endconnectivity. When using Cliques or Tiles, with a limited number offrequencies and a limited number of transceivers, the network may becomepartitioned. To avoid this, one transceiver can be assigned a “Blanket”channel. The Blanket assignment, usually to the channel with the best RFproperties, attempts to dynamically find a common frequency across allneighbors and by extension across the whole network. This is not apredetermined frequency, but merely a common channel to the neighbors.The communication network will still work if there is no assignedBlanket channel, because the network can still be connected withtransceivers assigned only through Clique or Tile Eligibility.

The FA sub-module can also perform an Evacuation and Reconstitutionfunction. The evacuation and reconstitution procedure can be executedwhenever a Non Cooperative (NC) (e.g., a jammer) occupies a channel. Theprocedure of evacuation and reconstitution can include assigning thetransceiver that is on a jammed frequency a new allowed channel andcommunicating the channel switch to neighbors through Heartbeatmessages.

2) Neighbor and Link Maintenance in Multi-Frequency Systems: The LMmodule 125 may perform a second task to manage relationships withneighbors and the communication links on which to reach the neighbors.The concurrent assignment of multiple transceivers of a network nodeoften means that one neighbor can be reachable via two or more channels.The LM module 125 can differentiate and characterize these links bycreating link profiles, which are a unique parameterized description ofthe communication link. A link profile indicates link characteristics ofa communication link and can include one or more of an indication ofcommunication channel frequency, target node coverage by thecommunication channel, data rate of the communication, the bandwidth ofthe communication channel, and whether a transceiver currently assignedto the link is busy. Link profiles can provide an abstractrepresentation of the communication channel, data rate, even interface(e.g., neighbor nodes), that allows a multi-frequency, multi-rate andmulti-transceiver network node to compare and work with very differententities.

The LM module 125 can discover and bring up neighbors of the networknode 100 on certain link profiles if the communication link isbidirectional and stable. Heartbeat messages can be used to determinebi-directionality of the link and the current status of the link (e.g.,the link being up, down or attempting to come up). A Heartbeat messagecan list a network node's neighbors, the transceiver assignments of theneighbors and their link status to them. The LM module 125 can use areceived Heartbeat to bestow a configurable number of “points” to thestatus of the communication link. The number of points bestowed during aconfigurable (e.g., programmable) window can be used as a “score” thatis compared against one or more of an up threshold score and a downthreshold score to estimate link stability and determine link status. Inaddition, link quality to individual neighbors can be scored based onquantized Heartbeat received signal strength indication (RSSI), which isitself based on the physics of individual frequencies and theenvironment.

The LM module 125 can calculate a link cost to communicating to aneighbor using one or more of determined link quality, data rate andwhether the neighbor has a Blanket channel assignment. The LM module 125may assign a higher link profile cost to LDR links than high data rate(HDR) links because LDR transmissions incur significantly morecontention than HDR transmissions. The LM module 125 may assign agreater cost to a Blanket channel link in anticipation that the Blanketchannel link experiences greater contention than other links. Thus, forthe Blanket channel case, the LM module 125 assigns a higher cost to alink profile that provides coverage to all neighbor nodes and assignslower cost to a link profile with coverage to less than all of theneighbor nodes.

The LM module 125 may maintain one or more tables of neighbors and linkprofiles. These tables may include cross-reference information of linkprofile costs to neighbors. The minimum link cost to each neighbor canbe shared with the Routing module 150 that is primarily concerned withfinding the cheapest route to all destinations in the network. In someexamples, the LM module 125 can share information about every link toeach direct neighbor with the Packet Management module 130 that mapsmessage packet one-hop target nodes to the assigned transceivers.

3) Link and Route Maintenance in Multi-Rate Systems:

a) Hello Messages: In multiple data rate systems, network nodes maymaintain several link profiles to each one of their neighbors. Heartbeatmessages typically fill the role of determining the characteristics ofthe link profiles, but Heartbeat messages can increase in size withnetwork density. Maintenance of LDR links poses a problem of scalabilityfor dense networks: each node within LDR range may send Heartbeatmessages that can become large and which are transmitted at low datarate. To improve scalability of the network, the network node 100 canintersperse “Hello” messages with Heartbeat message. Hello messages areshortened Heartbeat messages that can be used to score link stability,while Heartbeat messages provide additional information regarding linkbi-directionality. In some examples, the LM module 125 sends a Heartbeatmessage for a specified (e.g., programmed) multiple of the Hello messagetransmission period.

b) Link State Routing: By interleaving of Heartbeat messages with Hellomessages, the Heartbeat messages are largely scalable because they canbe broadcast to only one-hop neighbors. Adopting a Link State routingprotocol in the network allows Heartbeat messages to be used for manyannex purposes, such as link quality estimation, frequency assignmentsand neighbor node discovery. Link State routing may periodically floodlink profile costs to build a view of the entire network. With the linkprofile cost information, each network node can perform a shortest-pathalgorithm and construct a tree to reach every target node destination atlowest cost, whether the costing is assessed by the hop count or byanother metric such as data rate.

C. Packet Management (PM)

A message packet received at the network node 100 may identify thetransmission mode (e.g., unicast, multicast, or broadcast) fortransmitting the message packet from the network node 100, and mayidentify the target nodes for the transmission. All message packetsoutgoing from the network node 100, originated at the MAC module 115 orotherwise, are handed to the PM module 130, which manages priorityqueues for each transceiver. The PM module 130 interacts with the AccessController thread 145 to which it feeds the next packets to betransmitted on each transceiver.

1) PM Queues: Each transceiver is allocated a priority queue made ofpFIFO buffers, where p is a positive integer and is the number of packetpriorities defined in the system. For instance, the network may defineten priorities and Heartbeats/Hellos are given a higher priority fortransmission than video traffic.

The length of the priority queues can be configurable and can bespecified such that the inherent delays at underlying layers (e.g.,Access Controller, Access Worker and PHIY layers) are abstracted.Packets waiting to be transmitted in the priority queue can also beaggregated by the PM module 130.

2) PM's Neighbor Cover (NbrCvr): The PM module can map a messagepacket's next-hop target nodes to a set of link profiles assigned to thenetwork node's transceivers. This task is handled by the NbrCvr processof the PM module 130. Multicast packets are particularly challengingbecause there usually exists more than one set of link profiles to coverall targets. The PM module 130 identifies a link profile solution setthat includes a set of link profiles corresponding to communicationlinks such as for multicasting of the message packet. The link profilesolution set minimizes a certain cost function while maximizing coverageof all the network node targets. Identifying the solution set is akin toa solving a constrained set cover problem that is NP-complete.Constraints on the solution reflect the nature of multi-frequency,multi-rate, multi-transceiver networks. For instance, link profiles ofLDR links may cover many or all target nodes but are highly undesirablefrom a channel access perspective because they can increase contention.The NbrCvr process of the PM module 130 receives the list of neighbors,link profiles and link costs from the LM module 125 and may use a greedyalgorithm to determine the best link solution set to reach the next-hoptarget nodes.

FIG. 2 illustrates an example of message packet routing taking intoaccount multiple data rates of available communication links. In theFigure, HDR links (a-b), (a-c), (c-d), (b-e) and (d-e) are assignedlower link profile costs than LDR links (a-d) and (a-e) because of LDRcontention. The example shows the case when a network node (a) has aLDR-only neighbor node (e) that it can also reach through a multi-hopHDR route. Node (a) will originate and send LSU even though it has nouse for the LDR link as it will route unicast packet messages throughthe lower profile cost multi-hop route of (a-c-d-e).

The PM module 130 maps the link profiles of the link profile solutionset to at least a portion of the plurality of transceivers, andinitiates transmission of the message packet using the communicationlinks corresponding to the link profile solution set. The PM module 130may clone the original message packet to go out on differentcommunication links, and may track the clone and parent packettransmissions.

3) Multi-Link: NbrCvr greedily finds the link solution set with thelowest aggregate cost to reach a packet's targets. Multi-Link helps todistribute the load among all the transceivers of the network node 100.The need for Multi-Link is best illustrated in the following unicastexample, although the same argument can be made for multicast. If apacket has only one target. NbrCvr may repeatedly find the optimal linkprofile to reach it, even if the continuous transmission on thistransceiver starts causing contention on the selected channel. Changesin the local network are not immediately indicated by the Routing module150 because of the weight of constantly updating routes. However, theMAC module 115 may have sufficient information local to the module todecide whether less optimal link solution sets may also be acceptable. Aqueue level (e.g., the amount of packets residing in the queues of thetransceivers) can be an indicator of network contention and linkprofiles whose transceivers are deemed “busy” may be less attractivethan other link profiles. Multi-Link shifts the burden of transmissionfrom busy transceivers to less active transceivers in order to leveragemultiple link profiles to a message packet destination. Multi-Link canwork in conjunction with NbrCvr to ensure that transceivers of thenetwork node 100 receive equal and fair use whenever possible.

The NbrCvr process can increase one-hop unicast throughput by a factorof x, where x is the number of assigned HDR link profiles between thesource node and the target node of a unicast message.

D. Access

The Access module 135 of the network node 100 is composed of an AccessController sub-module 145 and an Access Worker sub-module pertransceiver. The functionality of the Access Worker sub-modules isidentical except they service different transceivers. The AccessController sub-module 145 assigns the channels for each transceiverAccess Worker sub-module based on commands received from the FAsub-module of the LM module 125. In turn, the Access Worker sub-modulesmay interact with a PHY layer Application Program Interface (API) thatmay provide transmit, receive and transceiver tuning capabilities.

The network medium access protocol can be based on Carrier SenseMultiple Access with optional Collision Avoidance (CSMA/CA). An approachto medium access using CSMA can be found in IEEE standard 802.11. AccessWorker sub-modules that control an unassigned transceiver may performthe channel scanning function described elsewhere herein. Otherwise,message packets can be pulled from short queues of the transceivers bytheir corresponding Access Worker sub-module. The short queues of thetransceivers are different from the priority queues. Pulling the messagepackets using an Access Worker thread allows transceivers to runC(SMA/CA independently. To increase reliability in transmission, in someexamples Access Worker sub-modules send broadcast packets twice.

For unicast message packets, the acknowledge (ACK) mechanism can dependon the Class of Service (CoS) assigned to the packet by the PM module130. For Unreliable CoS, no acknowledgement is expected when sending aunicast message packet. Conversely, for the Reliable CoS, the number oftransmission attempts can be configurable, which allows the sendingnetwork node to be wait-blocked waiting for an ACK. The network orsystem may define a promiscuous unicast transmission mode in which allneighbors keep the message packet if they receive it. Only the neighbornode specified as the unicast target node is tasked with sending an ACKframe to the promiscuous unicast transmission if requested. Transmissionresults can be returned to the PM module 130 for message packetdisposal.

The Access module 135 may support an over-the-air QoS differentiationscheme, which allows higher priority traffic to gain quicker access to achannel. The MAC module 115 may prioritize channel access where eachlevel of priority has a separate minimum and maximum priority contentionwindow (e.g., a higher priority level receives a lower contentionwindow). A back-off mechanism for each priority level may follow similarrules.

Multi-Frequency Systems

The issue of neighbor node coverage in system that uses multiplefrequencies concurrently on parallel transceivers is especially acutefor broadcast message traffic. For broadcast traffic, it may bedesirable for the MAC module 115 to reach all one-hop destinations withas few transmissions as needed and make use of redundant links in adynamic environment. The NbrCvr process of the PM module 130 providescoverage of next-hop targets in the frequency space, and Multi-Linkhelps provide frequency diversity in the system.

A. PM's NbrCvr:

The PM module 130 uses the NbrCvr process to map target nodes for amessage packet to a set of link profiles (called the “link profilesolution set” or more simply “solution set”) on which to reach thetarget nodes. The PM module 130 receives neighbor and link profileinformation from the LM module 125, including a link profile cost ofeach neighbor on particular communication links. The NbrCvr process canbe implemented as a software module in the PM module 130 and a call tothe NbrCvr process can include the list of next-hop target nodeidentifiers (IDs). The NbrCvr process determines a link profile solutionset that includes one or more communication channels that maximizecoverage of the target nodes at minimized cost.

FIG. 3 shows an example of an implementation of neighbor node and linkprofile structures maintained by the NbrCvr process. The link profilestructures can include lists of direct neighbor nodes of the networknode 100, link profiles, and cross references of the link profiles thatcan be used to reach neighbors. Note that information on the networknode 100 itself may be included in the data structures. The NbrCvrprocess can use a specialized greedy algorithm (described elsewhereherein) that tries to cover all target nodes for a message packet andreturns the link profile solution set for the target node coverage. Thelink profile solution set can be stored as an array stored in memory. Anexample of such an array may include the following for a link profilethat is at least part of the solution set: the ID of the link profile,the number of target nodes covered using the link profile, the IDs ofthe target nodes, the transmission mode (e.g., unicast or broadcast) ofthe clone message packet if the link profile is used to send a clonerather than a parent message packet, and the promiscuousness of theclone (e.g., promiscuous unicast or not).

The link profile solution set can be entered into a cache memory. Thiscan prevent running the NbrCvr greedy algorithm over again for the sameset of target nodes. The PM module 130 can check for a cached solutionset before calling the NbrCvr process. The NbrCvr process of the PMmodule 130 may assess whether a broadcast message packet should beconverted to a set of unicast or promiscuous unicast message packets. Ifso, the PM module 130 may clone as many copies of the parent packet asthere are unicast and broadcast frames on each link profile. The PMmodule 130 can manage transmission of the clone message packets ascommunication links and target nodes change status to up and down.

1) Destinations: A call to the NbrCvr process may specify one or more ofthe following: an address of a target node for a unicast message packet,a list of target nodes for a multicast message packet, a list of targetnodes for a broadcast message packet, and a specific link profile ID(for no target destination).

In the case of a unicast packets and multicast packets, the NbrCvrgreedy algorithm will attempt to cover the specified targets. Otherwise,for a broadcast packet, the NbrCvr process keeps track of the directneighbors of the network node 100 to translate the packet's broadcastaddress destination into a list of target IDs. The NbrCvr process thentreats the broadcast packet in the same manner as it would a multicastpacket.

Heartbeat message packets and Hello message packets are handleddifferently because the link profile ID of the transmission matters morethan the target destinations; some of which may be unknown. Thesemessage packets typically are transmitted according to a specific linkprofile that they maintain. For these packets, the NbrCvr process maybypass the coverage algorithm and simply ensure that it has the linkprofile ID specified by the Heartbeat or Hello in its store (e.g.,memory). In this case, the NbrCvr may then return without running itscoverage algorithm.

2) NbrCvr Algorithm: The NbrCvr algorithm may start by parsing the listof target destinations and filling a neighbor node Cost Table(hereinafter “Cost Table”) that contains link profile coverage, linkprofile cost, and an indication of busy-ness of the link. Link profilecost can be determined using link characteristics. Some examples of linkcharacteristics that can be used to determine link profile cost includethe target node coverage and the data rate. A higher link profile costcan indicate a less desirable link profile for transmitting the messagepacket.

Table I is a representation of an example of a Cost Table generated bythe PM module 130 and used by the NbrCvr process to determine a linkprofile solution set.

TABLE I Sec Nbrs N₀ . . . N_(n) Busy AggCost nCov 0 LP₀ C₀₀ . . . C_(0n)B₀ Σ C_(.0) |C_(.0)| LP₁ C₁₀ . . . C_(1n) B₁ Σ C_(.1) |C_(.1)| 1 LP₂ C₂₀. . . C_(2n) B₂ Σ C_(.2) |C_(.2)| . . .

In the Table, N_(i),

εN, is the set of targets, which may be reached by each link profileLP_(j);

εN at a cost of C_(j,i). A cost of C_(j,i)=0 means that neighbor i isnot available on link profile j, (LP). The “Busy” field” of a linkprofile j can be indicated by a Boolean variable that is assigned avalue of “true” if the transceiver to which link profile j is assignedis in a busy state. The aggregate cost (AggCost) can be a function ofall costs of LP_(j) to the target nodes. In the example shown in theTable, the function is the sum of all costs, but the function couldinclude the average cost, median cost or a cardinality to representdifferent network constraints. The number of targets covered by a linkprofile (nCov) is used to break ties that occur when the aggregate costis determined to be the same for two or more link profiles.

A link profile can be selected according to lowest link profile costfrom among unselected link profiles of the cost table. For example, theCost Table may order the link profiles according to the link profilecosts and the link profiles are examined in order according to thetable. The NbrCvr algorithm can include traversing the Cost Table (e.g.,iteratively) to examine each link profile and determine whether nodecoverage by the link profile is still needed to cover all targets.However. NbrCvr algorithm differs from a traditional set cover greedyalgorithm in which an element (here a link profile) with the maximumcoverage would be selected at every iteration. This is because linkcharacteristics such as blanket channel assignments, busy transceivers,and multiple data rates impose new constraints that preclude the NbrCvrprocess from using existing greedy algorithms.

In the absence of NCs and when implementing a normal blanket networkinterconnection, all network nodes assign one transceiver to the Blanketcommunication link. In this case, not only is the blanket channelexpected to be more frequently used (because of availability to allnodes), a network node may reach every one of its neighbor nodes usingonly the Blanket link. A typical greedy algorithm would always selectthe link profile assigned to the Blanket link, thereby increasingcontention on the Blanket channel. Therefore, an NbrCvr algorithm shouldrecognize the network environment in which it has been implemented. TheNbrCvr process considers Blanket link profiles, if available, as lessdesirable for packet transmission than non-Blanket (e.g., Tile orClique) link profiles. Non-busy link profiles are preferred over busylink profiles.

The Cost Table of NbrCvr can be divided into non-Blanket and Blanketsections (Sec in the Table) that can include the relevant link profilesthat can represent the constraints imposed by the network. Thenon-Blanket section can be above the Blanket section (or otherwiseplaced in a position of earlier consideration). This causes, all otherthings being equal, any Tile or Clique link profiles to be consideredfirst. Within the same section of a Cost Table, link profiles can beordered according to increasing aggregate cost such that less costlylinks may be considered before the other links. If two link profileshappen to have the same aggregate cost. NbrCvr can use the number ofneighbors reached using the link profile to break the tie.

More network nodes can be disrupted when a unicast packet is sent on alink profile connected to more neighbor nodes. On the other hand,multicast or broadcast packets may reach more target nodes if the linkprofile is well connected. Therefore, NbrCvr may favor link profileswith fewer neighbors for unicast packets, and favor link profiles withmore neighbors for multicast and broadcast.

The NbrCvr algorithm may start with an empty link profile solution setS=Ø, and may traverse the Cost Table by rows, section by section, andlink profile by link profile. The selected link profile is added to thelink profile solution set when the selected link profile increases thenumber of target nodes covered by the link profile solution set. For thecase when the next lowest cost link profile examined by the NbrCvralgorithm covers at least all the neighbors already covered (e.g., thetarget nodes covered by the previously selected link profiles are asubset of the target nodes covered by the currently selected linkprofile), the link profiles currently in the link profile solution set Sare dropped or otherwise removed. If the target nodes cannot all becovered using the link profiles within the section Cost Table currentlybeing examined, the NbrCvr algorithm may advance to the next section inwhich it orders the link profiles. The NbrCvr process may stop once alltarget next-hop neighbors are covered, possibly before all the linkprofiles in the Cost Table have been examined. In some examples, theNbrCvr process stops when traversal of the Cost Table is completed. Forthis situation, the NbrCvr process may generate an indication of thetarget nodes not covered by the link profile solution set

Whenever a link profile LP_(k) is considered for adding to the linkprofile solution set S, the NbrCvr algorithm may iterate through thesolution set S to look for redundant node coverage by other linkprofiles in the solution set. If the coverage by a link profile LPjεS isfound to be included in the coverage afforded by LPk, LPj may be purgedfrom the solution set S. This allows redundant link profiles to beeliminated to whenever a link profile is considered to be added to thesolution set S. Removing redundant link profiles can remove unnecessarypacket transmissions.

3) Pseudo-Code and Example: The Appendix includes an example ofpseudo-code of an example of an NbrCvr greedy algorithm. The pseudo-codeexample is simplified for space and to simplify explanation. Whendetermining whether coverage provided by a link profile is needed, theimplementation of the NbrCvr algorithm makes optimizations aimed attraversing a Cost Table only once to determine a link profile solutionset.

Table II is another representation of an example of a Cost Tablegenerated by the PM module 130. Table II is an example of a Cost Tablefilled by a PM module 130 of a network node 100 attempting to send apacket to five neighbors {N₀, N₁, N₂, N₃, N₄} on four link profiles{LP₀, LP₁, LP₂, LP₃}.

TABLE II Sec Nbrs N₀ N₁ N₂ N₃ N₄ AggCost 0 LP₀ 1 1 LP₁ 1 1 2 LP₂ 2 2 4 1LP₃ 3 3 3 3 12

The Cost Table in the example includes two sections: Section 0 for Tileor Clique assignments and Section 1 for Blanket assignments. Adescription of operation of an NbrCvr greedy algorithm on the Cost Tablefollows. The notation cov(LPf) denotes target node coverage by linkprofile j (LPj), and cov(S) denotes target node coverage by the solutionset S.

1) [Examine New Section 0] LP₀ brings additional coverage to (empty)solution set S: add LP₀ to S.

-   -   =>S={LP₀} and cov(S)=[0, 1, 0, 0, 0], where “1” signifies        coverage of neighbor node N₁.

2) LP₁ brings additional coverage to solution set: add LP₁ to S.

Iteration through S to determine redundant coverage:

-   -   i) cov(S)−cov(LP₀)<cov(S): keep LP₀ in S.    -   =>S=[LP₀; LP₁] and cov(S)=[1, 1, 1, 0, 0].

3) LP₂ brings additional coverage to solution set: add LP₂ to S.

-   -   Iteration through S:    -   i) cov(S)−cov(LP₀)=cov(S): remove LP₀.    -   ii) cov(S)−cov(LP₁)<cov(S): keep LP₁.    -   =>S={LP₁; LP₂} and cov(S)=[1, 1, 1, 1, 0].

4) [Examine New Section 1] LP₃ brings no additional coverage to solutionset S.

-   -   =>S={LP₁; LP₂} and cov(S)=[1, 1, 1, 1, 0].

In this example, N₄ cannot be covered by any link profile. The NbrCvrprocess found the two link profiles that could cover all reachabletargets at the lowest cost.

4) Solution Set Caching: NbrCvr can be called for every packettransmission, and many of the packets are intended for the same targetnodes. This may place an undue burden on the NbrCvr process torecalculate identical solution sets many times. A cache can beimplemented, such as in a specified area of memory, by the NbrCvrprocess and the cache can be checked for valid solution sets beforeattempting to run through the greedy algorithm. The NbrCvr process canuse a stored link profile solution set on a subsequent message packetwhen the target nodes of the subsequent message packet match the targetnodes of the stored link profile solution set.

The cache can be indexed by a signature of the list of targets.Different target lists map to different cache entries through a hashfunction. To be consistent across message packets, the list of targetnodes can be ordered by node ID so that target nodes out of order leadto the same cache entry and same link profile solution set. When achange in the nodes that neighbor the network node occur, the cache canbe flushed or otherwise cleared of link profile solution sets stored inthe cache. Some examples of a change to cause a cache flush includes aneighbor node appearing or disappearing on a link profile, a fluctuationin link profile cost, etc. In effect, anytime the LM module 125 callsthe NbrCvr process of the PM module 130 to modify the neighbor or linkstores, the cache can be invalidated.

5) Techniques for Non-Unicast Transmissions: Over-the-air broadcasttransmissions are necessarily sent unreliably because a packet sourcedoes not know whether the packet has been successfully received by thedestination nodes. The NbrCvr of the PM module 130 may includetechniques to bring a higher degree of delivery reliability to broadcasttransmissions. Two examples of these techniques are “broadcastbranching” and “K-reliability.”

a) Broadcast Branching: A disadvantage of multicast traffic is itsdependence on unreliable one-hop broadcast transmissions. Routing treescan be built such that one target (usually close to the trafficoriginator) is a relay node for a number (e.g., tens) of other multicasttargets. When the number of one-hop targets is relatively high, theRouting tree can adjust to delivery failure since the message packetwill be widely repeated. On the other hand, for a packet loss to two orthree target nodes multicast traffic does not provide for packetrecovery and the data cannot be delivered to the rest of the Routingtree.

Broadcast branching converts a multicast message packet sent to N≦θ_(B)targets into N clones of the message packet and transmits the N clonesas N promiscuous unicast packets. The PM module 130 may use θ_(B)=2,which means that a packet intended for one or two targets will becarried by as many promiscuous unicast packets as targets. The“promiscuousness” ensures that a node keeps and processes a packet thatis intended for another target.

b) K-Reliability: The K-Reliability technique hypothesizes thatmulticast transmission failure occurs because most or all target nodesexperience a collision with one other message packet. If a unicastpacket could be sent to one of the affected targets, other nodesexperiencing failure would benefit from the ensuing retransmissionattempts. K-Reliability picks K targets from among packet's N next-hopdestinations to be a proxy for the overall status of the multicasttransmission. Any of the K target nodes that successfully receive thepacket message initiates an acknowledge message packet. K-Reliabilityconverts a multicast packet with N targets into min(K; N) promiscuousunicast packets, where K may be configured to any integer (e.g.,reasonable values of K are 1, 2 or 3). As described previously herein,the MAC module may attempt two transmissions for broadcast packets. Avalue of K=1, can cause one to two over-the-air transmissions, dependingon the outcome of the first attempt. By the same logic, K=2 will matchor exceed the number of transmissions of regular broadcast packets.

B. PM's Multi-Link:

Multi-Link leverages multiple assigned transceivers with differentfrequencies to one or several target neighbors. This allows theconcurrent transmission of packets on multiple links to balance thecommunication load, which increases throughput and reduces message delayand channel contention. Multi-Link attempts to balance the load ontransceivers that can reach the same target node. To accomplish this,the order in which the NbrCvr process considers adding link profiles toa link profile solution set is modified. Link profiles assigned to“busy” transceivers are less desirable than transceivers under a lighterload (e.g., not busy or less busy). The NbrCvr process may create “busy”sections in the Cost Table, and link profiles in non-busy sections areconsidered before link profiles in busy section (such as by placing busysections below “non-busy” sections in the Cost Table). In this way, linkprofiles associated with busy transceivers given a higher cost than linkprofiles associated with non-bust transceivers.

Monitoring the status of queues of the transceiver can be used as aproxy for determining contention on a channel. A state of a transceivercan be defined as busy when the level of its cumulative queues (e.g.,long queue and short queue) exceeds a predefined High-Water Level (HWL).The level can be determined according to one or both of the amount ofdata to be sent or the number of packet messages to send. For example, abusy state can be assigned to a transceiver by the packet managementmodule 130 when a number of packets in a message queue of thetransceiver exceeds a first specified packet number (HWL) and a non-busystate when the number of packets in the queue decreases to a secondspecified packet number (LWL). Having different values of HWL and LWLadds some hysteresis to transceivers going into and out of the busystate, but the values for HWL and LWL can be specified (e.g.,programmed) to be the same value. Transceivers can return to a non-busystate when the queue level dips below a Low-Water Level (LWL). Ineffect, the HWL sets how long a transceiver waits before triggeringMulti-Link, and LWL helps ensuring that all transceivers will becontinuously solicited.

FIG. 4 illustrates an example of mechanisms of Multi-Link as transceiverqueues fill up and empty. In this simplified example of twotransceivers, the Blanket communication channel is assigned totransceiver X₀ and X₁ is a non-Blanket transceiver. The queues of bothtransceivers start empty (LWL mode), and the NbrCvr process prefers thenon-Blanket transceiver X₁ according to the Cost Table. The X₁ queuefills up gradually as new packets arrive and other packets are sent onthe communication channel assigned to X₁. If the queue level exceedsHWL, is changed to a busy state and the NbrCvr process selects X₀because it is still in LWL mode and is in a non-busy state. When trafficon X₀ causes X₀ switches to HWL mode (and as long as X₁ is also still inHWL mode), the Blanket assigned transceiver loses its advantage over theX₁ transceiver, on which new packets are then placed. In order to keepthe NbrCvr cache of the PM module 130 valid through the frequent HWL-LWLchanges, the busy state of the transceivers can be added to the hashfunction mapping of link profile solution sets stored in the cache,which includes target node IDs.

Multi-Rate Systems

The network may use concurrent multiple data rates. A transceiver canallocate only one frequency at a time, but it may have more than onedata rate at a time. The network node 100 can maintain Low-Data-Rate(LDR) links because they have a significantly greater range thanHigh-Data-Rat e (HDR) links, which is useful in networks with militaryapplications. However, sending at LDR occupies the communication channelfor much more time than at HDR. In itself, the maintenance of neighbornodes on LDR links can damage the ability of large networks to fulfilltheir role or to even stay up.

Although the methods and example are described herein mostly in terms ofmulti-frequency systems, the NbrCvr process can work equally well inmulti-rate network environments. The NbrCvr process can easily beextended to support multiple data rates by placing LDR link profiles inseparate sections and moving them to the higher cost section (e.g., thebottom) of the Cost Table. This means that LDR link profiles are thelast to be considered by the NbrCvr greedy coverage algorithm. TheNbrCvr process can define the following sections (shown here for thecase of two data rates and Busy/non-Busy), in the following defaultorder:

0: HDR, Non-Blanket, non-Busy

1: HDR, Blanket, non-Busy

2: HDR, Non-Blanket, Busy

3: HDR, Blanket, Busy

4: LDR, Non-Blanket, non-Busy

5: LDR, Blanket, non-Busy

6: LDR, Non-Blanket, Busy

7: LDR Blanket, Busy

The section order can be modified through modification of one or both ofthe LM module 125 and the PM module 130.

Methods

FIG. 5 is a flow diagram of a method 500 of operating a communicationnetwork that includes multi-transceiver network nodes. At block 505, atleast one message packet is received at a network node of acommunications network. The message packet identifies network nodetargets for transmitting the message packet. The network node includes aplurality of transceivers, and the message packet may identify networknode targets for multicasting the message packet to target nodes. Incertain examples, the message packet identifies network node targets forbroadcasting the message packet. In certain examples, the message packetidentifies network node targets for unicasting the message packet.

At block 510, the network node produces link profiles associated withcommunication links available to the network node. The link profiles arean abstraction of the characteristics of the communication link, and caninclude a busy indication of whether a transceiver currently assigned tothe communication link is in a busy state and an indication of nodesavailable to interface with the network node. The interface for the nodecan be determined by link maintenance using one or both of heartbeatmessages and hello messages.

At block 515, equivalent link profiles are identified that are suitablefor message packet transmission. These link profiles can be used to sendtraffic from the network and the busy state indicates the link profilesexperiencing less contention. This can create a pool of link profilesfor initiating multiple simultaneous transmissions. The link profiles inthe pool can be somewhat homogeneous (e.g., have the same data rate),but do not necessarily have to have equivalent performance.

At block 520, a link profile solution set is identified that includes aset of link profiles corresponding to communication links fortransmitting the message packet. The link profile solution set maximizescoverage of the network node targets, such as maximizing coverage formulticasting of the message packet. The link profile solution set can bedetermined according to link profile cost using a greedy algorithmparticularized for one or both of a multi-frequency and multi-data ratenetwork. Lower cost can be accorded to a communication link with ahigher data rate even though the link may not provide complete coverageto the target nodes. Cost can also be determined using a busy state ofthe transceiver assigned to the communication link; with links having abusy transceiver assigned a higher cost than links with a non-busytransceiver.

At block 525, the link profiles of the link profile solution set aremapped to at least a portion of the plurality of transceivers. Thetransceivers can be assigned to communication links by packetmaintenance. At block 530, the message packet is transmitted using thecommunication links corresponding to the link profiles of the linkprofile solution set. In certain examples, one or more clones of themessage packet are generated and transmitted to provide coverage to thetarget nodes. In certain examples, the cloned messages are transmittedusing a combination of multicasting and unicasting of the messagepacket.

The network node may be part of a portable wireless communicationdevice, such as a personal digital assistant (PDA), a laptop or portablecomputer with wireless communication capability, a web tablet, awireless telephone, a wireless headset, a pager, an instant messagingdevice, a digital camera, an access point, a television, a medicaldevice (e.g., a heart rate monitor, a blood pressure monitor, etc.), orother device that may receive and/or transmit information wirelessly.Multiple portable communication devices may be implantable into anetwork having a military application.

In some embodiments, the portable wireless communication device mayinclude one or more of a keyboard, a display, a non-volatile memoryport, multiple antennas, a graphics processor, an application processor,speakers, and other mobile device elements. The display may be an LCDscreen including a touch screen.

In some embodiments, the network node may be a communication node for awired communication system. The wired system can include multipledifferentiable communication links between nodes that make use ofmultiple wired transceivers. Transmitting messages using differentcommunication links may be associated with different costs.

The embodiments described herein may be implemented in one or acombination of hardware, firmware and software. Embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described. A computer-readable storage device mayinclude any non-transitory mechanism for storing information in a formreadable by a machine (e.g., a computer). For example, acomputer-readable storage device may include read-only memory (ROM),random-access memory (RAM), magnetic disk storage media, optical storagemedia, flash-memory devices, and other storage devices and media. Insome embodiments, system 100 may include one or more processors and maybe configured with instructions stored on a computer-readable storagedevice. The Abstract is provided to comply with 37 C.F.R. Section1.72(b) requiring an abstract that will allow the reader to ascertainthe nature and gist of the technical disclosure. It is submitted withthe understanding that it will not be used to limit or interpret thescope or meaning of the claims. The following claims are herebyincorporated into the detailed description, with each claim standing onits own as a separate embodiment.

APPENDIX NbrCvr Algorithm Pseudo-Code Example nbrCvrGreedy(targets):currentSection = 1; lpId = 0; numCvdTargets = 0; solSet = Ø; costTable =Ø; /*Fill cost table*/ costTable = fillcostTable(targets); while((numCvdTargets < numTargets) and (currentSection < numSections)) do  ifnewSection then    /*This is a new section*/    currentSection++;   /*Order the section*/  quickSort(costTable, currentSection);  /*Findthe next lp*/  lpId = nextLp(costTable, currentSection);  iflisNeeded(solSet, lpId)) then    /*This lp brings no new coverage*/ ;   continue;  if lisSolSetRedundant(solSet, lpId) then    /*This lpbrings no new coverage*/ ;    solSet = Ø;  insertLp(solSet, lpId); numCvdTargets = findNumCvdTargets(solSet);  /*Check all lps in solSetare still needed*/ ;  for ssLpId in solSet do    iflisNeeded(removeLp(solSet, ssLpId), ssLpId) then      /*lp is redundant,remove*/ ;      solSet = removeLp(solSet, ssLpId);

What is claimed is:
 1. A network node comprising: a plurality oftransceivers, wherein at least one transceiver is configured to receiveat least one message packet via the communication network, wherein themessage packet identifies network node targets for multicasting of themessage packet; and a controller, wherein the controller includes: alink management module configured to produce link profiles associatedwith communication links available to the network node, wherein a linkprofile indicates link characteristics of a communication link andincludes a busy indication of whether a transceiver currently assignedto the communication link is in a busy state, and configured to identifyequivalent link profiles suitable for transmitting the message packet;and a packet management module configured to: identify a link profilesolution set that includes a set of link profiles corresponding tocommunication links for multicasting of the message packet, wherein thelink profile solution set maximizes coverage of the network nodetargets; map the link profiles of the link profile solution set to atleast a portion of the plurality of transceivers; and initiatetransmission of the message packet using the communication linkscorresponding to the link profile solution set.
 2. The network node ofclaim 1, wherein the link profile indicates a communication channelfrequency, a data rate of the communication channel, target nodecoverage by the communication channel, and the busy indication, whereinthe packet management module is configured to determine the link profilesolution set using a link profile cost determined using at least thetarget node coverage, the data rate, and the busy indication, andwherein a higher link profile cost indicates a less desirable linkprofile for transmitting the message packet.
 3. The network node ofclaim 1, wherein the packet management module is configured to: assign abusy state to a transceiver when a number of packets in a message queueof the transceiver exceeds a specified packet number; and assign anon-busy state to the transceiver when the number of packets in thequeue decreases to the specified packet number.
 4. The network node ofclaim 1, wherein the packet management module is configured to: assign abusy state to a transceiver when a number of packets in a message queueof the transceiver exceeds a first specified packet number; and assign anon-busy state to the transceiver when the number of packets in thequeue decreases to a second specified packet number, wherein the secondspecified packet number is less than the first specified packet number.5. The network node of claim 1, wherein the packet management module isconfigured to: order link profiles into a cost table according to a linkprofile cost determined using the link characteristics, wherein a higherlink profile cost indicates a less desirable link profile fortransmitting the message packet; and traverse the cost table beginningwith the lowest cost link profiles to determine the link profilesolution set, wherein the link profile solution set includes one or morecommunication channels that maximize coverage of the target nodes atminimized cost.
 6. The network node of claim 5, wherein the packetmanagement module is configured to: place a link profile in a busysection of the cost table when a transceiver assigned to the linkprofile has a busy state; place a link profile in a non-busy section ofthe cost table when the transceiver assigned to the link profile changesto a non-busy state; and traverse the non-busy section of the cost tablebefore traversing the busy section of the cost table.
 7. The networknode of claim 5, wherein the packet management module is configured to:select a link profile according to lowest link profile cost from amongunselected link profiles of the cost table, wherein a link profileassociated with a transceiver in a busy state is given a higher costthan a link profile associated with a transceiver in a non-busy state;add the selected link profile to the link profile solution set when theselected link profile increases the number of target nodes covered bythe link profile solution set; remove a previously selected link profilefrom the link profile solution set when the target nodes covered by thepreviously selected link profile are a subset of the target nodescovered by the currently selected link proflile; and stop the selectingof link profiles when the link profile solution set covers all of thetarget nodes or when transversal of the cost table is comlplete.
 8. Thenetwork node of claim 5, wherein the packet management module isconfigured to identify any target nodes not covered by the link profilesolution set.
 9. The network node of claim 1, including a memoryintegral to or in electrical communication with, the controller, andwherein the packet management module is configured to: store the linksolution set in a specified area of memory; use a stored solution set ona subsequent message packet if the target nodes of the subsequentmessage packet match the target nodes of the stored link solution set;and map the subsequent message packet to a stored link solution setusing a hush function, wherein the hush function includes an indicationof the busy state of a transceiver included in a stored solution set.10. The network node of claim 9, wherein the link management module isconfigured to determine nodes that neighbor the network node, andwherein the packet management module is configured to clear any linkprofile solution sets stored in the specified area of memory in responseto a determined change in the nodes that neighbor the network node. 11.The network node of claim 1, wherein the link profile solution setidentifies communication channels that maximize coverage of the networknode targets when multicasting the message packet.
 12. The network nodeof claim 1, wherein the link profile solution set identifiescommunication channels for use in unicasting of the message packet. 13.A method comprising: receiving at least one message packet at a networknode of a communications network, wherein the message packet identifiesnetwork node targets for transmitting the message packet and the networknode includes a plurality of transceivers; producing, by the networknode, link profiles associated with communication links available to thenetwork node, wherein a link profile indicates link characteristics of acommunication link, and wherein the link characteristics include a busyindication of whether a transceiver currently assigned to thecommunication link is in a busy state; identifying equivalent linkprofiles suitable for transmitting the message packet; identifying alink profile solution set that includes a set of link profiles to assignto transmitting the message packet, wherein the link profile solutionset maximizes coverage of the network node targets; mapping the linkprofiles of the link profile solution set to at least a portion of theplurality of transceivers; and transmitting the message packet using thecommunication links corresponding to the link profiles of the linkprofile solution set.
 14. The method of claim 13, wherein producing alink profile includes producing a link profile that indicates acommunication channel frequency, a data rate of the communicationchannel, target node coverage by the communication channel, and the busyindication, wherein identifying the link profile solution set includesdetermining the link profile solution set using a link profile costdetermined using at least the target node coverage, the data rate, andthe busy indication, and wherein a higher link profile cost indicates aless desirable link profile for transmitting the message packet.
 15. Themethod of claim 13, including: assigning a busy state to a transceiverwhen a number of packets in a message queue of the transceiver exceeds aspecified packet number; and assigning a non-busy state to thetransceiver when the number of packets in the queue decreases to thespeciied packet number.
 16. The method of claim 13, including: assigninga busy state to a transceiver when a number of packets in a messagequeue of the transceiver exceeds a first specified packet number; andassigning a non-busy state to the transceiver when the number of packetsin the queue decreases to a second specified packet number, wherein thesecond specified packet number is less than the first specified packetnumber.
 17. The method of claim 13, wherein identifying the link profilesolution set includes: ordering, by the network node, link profiles intoa cost table according to a link profile cost determined using the linkcharacteristics; placing a link profile in a busy section of the costtable when a transceiver assigned to the link profile has a busy state;placing a link profile in a non-busy section of the cost table when thetransceiver assigned to the link profile changes to a non-busy state;and traversing one or more non-busy sections of the cost table beforetraversing one or more busy sections of the cost table to determine thelink profile solution set, wherein the link profile solution setmaximizes coverage of the network node targets at minimized cost.
 18. Asystem comprising: a communication network including a first networknode and a plurality of nodes that neighbor the first network node,wherein the first network node includes: a plurality of transceivers,wherein at least one transceiver is configured to receive at least onemessage packet via the communication network, wherein the message packetidentifies network node targets for multicasting of the message packet;and a controller, wherein the controller includes: a link managementmodule configured to produce link profiles associated with communicationlinks available to the network node, wherein a link profile indicateslink characteristics of a communication link and includes a busyindication of whether a transceiver currently assigned to thecommunication link is in a busy state; and a packet management moduleconfigured to: identify a link profile solution set that includes a setof link profiles corresponding to communication links for multicastingof the message packet, wherein the link profile solution set maximizescoverage of the network node targets; map the link profiles of the linkprofile solution set to at least a portion of the plurality oftransceivers; and initiate transmission of the message packet using thecommunication links corresponding to the link profile solution set. 19.The apparatus of claim 18, wherein the link profile indicates acommunication channel frequency, a data rate of the communicationchannel, target node coverage by the communication channel, and the busyindication, wherein the packet management module is configured todetermine the link profile solution set using a link profile costdetermined using at least the target node coverage, the data rate, andthe busy indication, and wherein a higher link profile cost indicates aless desirable link profile for transmitting the message packet.
 20. Thesystem of claim 18, wherein the packet management module is configuredto: assign a busy state to a transceiver when a number of packets in amessage queue of the transceiver exceeds a first specified packetnumber; and assign a non-busy state to the transceiver when the numberof packets in the queue decreases to a second specified packet number,wherein the second specified packet number is less than the firstspecified packet number.